In a wireless network, a HO (handover, handover) of a service node caused by movement of a UE occurs frequently, especially, in the future LTE (Long Term Evolution, long term evolution)-A system, the HO between nodes will become more frequently because of the introduction of plenty of LPN (Low Power Node, low power node) nodes.
“Positioning” is a service provided by the network side for a UE to pre-estimate precise position information, which is mainly used in some scenes related to social security, for example, arresting criminals, guiding escape routes, and etc. Therefore, the occurrence frequency of positioning service is relatively low. In the practical application, it is possible that the positioning process of a UE is in conflict with the handover process of the UE in the network, that is, the current UE not only needs to perform positioning but also needs to perform handover.
For the E-CID (Enhanced Cell-ID, enhanced Cell-ID positioning method) positioning manner, a frequently-used positioning method is a Rx (receiving time)-Tx (transmitting time) method. In the frequently-used positioning method, is the UE measures the CRS (Cell-specific reference signals, cell-specific reference signals) of the serving cell to estimate the Rx at the UE side, and transmits the uplink SRS (Sounding Reference Signal, sounding reference signal) signal to estimate the Tx at the UE side, thus the UE calculates the time difference of Rx-Tx at the UE side, and then reports the result to the serving eNB (evolved Node B, evolved base station). The serving eNB, by measuring the Rx-Tx time difference of itself, and then taking consideration of the Rx-Tx time difference reported by the UE side, may calculates the radius of a circle away from the service eNB on which the UE currently locates, and the serving eNB also measures the UE AOA (Angle of Arrival, angle of arrival), where the AOA is a relative angle between the radio wave signal transmitted by the terminal and the eNB reference direction, and is estimated by the eNB through the directive antenna or the array antenna. And then, the serving eNB reports the above obtained information to a positioning server, and the positioning server determines the precise position of the UE according to the above information.
In the process of implementing the invention, the inventor found that the prior art has the following disadvantages at least: when the UE carries out the E-CID positioning, the UE may has trigged a HO already, it means that the quality of the link between the serving eNB and the UE is poor, or even disconnected completely, therefore, the measurement result of the Rx-TX at the UE side can't been reported to the serving eNB, thereby causing a failure of the UE E-CID positioning.
The positioning server needs to initiate a positioning request to a new eNB after the UE successfully handovers to the new eNB, thereupon, it needs to add a mass of signaling between the eNB and the positioning server, and the positioning delay will be relatively long.